| Summary: | A 13～16 GHz bi-phase voltage variable attenuator(VVA) based on 0.25 μm gallium arsenide pseudomorphic high electron mobility transistors(GaAs pHEMT) process is presented. Balanced structure that adopt in this circuit provides less input output return loss. A cascade of T-attenuator and Pi-attenuator topologies are adopt in attenuator part. Parasitic reduce and linearity enhancement are achieved by using stacked double-gate switch transistor structure in shunt arms of T-attenuator and Pi-attenuator topologies. Simulated results show that in the range of 13-16 GHz, the input output return loss is less than -14 dB, the insertion loss is 12.5 dB, and the dynamic range is more than 20 dB, the input 1-dB power compression point(P1dB) is over 30 dBm while the chip area is 1.8 mm×1.2 mm.
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